Protect your fish during spring start-up by quickly and effectively controlling your pond's ammonia and nitrites with all-natural nitrifying bacteria. Also supports your biological filter throughout the season. Contains unique, patented strains of Nitrosomonas and Nitrobacter bacteria. Use when starting a new pond or starting up an established pond in the spring, adding new fish, changing water, changing filter media, after medicating or whenever ammonia or nitrite are detected. 16 oz treats 1417 gallons.